The invention relates to a cutting tool of modular construction for a machine tool. This tool consists of a cutting head, a shank and a coupling effective between shank and cutting head. By means of the shank, the tool is clamped in place in the tool receptacle, for example the chuck of a machine tool. The cutting head is detachably fixed to the shank by means of the coupling. Depending on the desired field of use, the cutting head can be configured as a boring head, milling head or reaming head. However, the cutting head may also be a cutting head for any other desired cutting process.
A cutting tool having a complicated coolant guide is known from DE 103 26 928 A belonging to the prior art. Here, a plurality of coolant passages are distributed over the periphery of the shank. The number of coolant passages corresponds to the number of blades on the cutting head. Via coolant bores in the cutting head, the respective coolant passages are conductively connected to their respectively associated blades. A disadvantage in this case is the reduction in the flexural strength of the shank which is associated with the large number of cooling passages. A further disadvantage is the fact that each shank embodiment can only be used jointly with a specific cutting head embodiment.
A cutting tool having a coolant guide consisting of a central coolant passage or coolant tube and a plurality of coolant passages is known from DE 10 20-05 03 1 683 A. The coolant passages are in this case configured as fitting bores or axial grooves in the end region of the shank or of a functional insert inserted at the end into the shank. A disadvantage in this case is the large number of cooling passages and the reduction in the flexural strength of the shank in the shank end region which is again associated with said large number of cooling passages.
In the tool known from DE 103 26 928 A, a clamping cone is used as coupling between cutting head and shank. Here, the effective surfaces are very small on account of the conical shape of the clamping cone. As a result of these small effective surfaces, only very low torques can be transmitted from the shank to the cutting head and vice versa. In addition, it is felt to be a disadvantage that the clamping surfaces, that is to say the conical surfaces of the clamping cone on the cutting head and the corresponding mating surfaces, are arranged very deeply in the shank. The surfaces cannot be seen from outside when inserting the cutting head. It is therefore possible for the surfaces to tilt when inserting the cutting head into the shank. This risk of tilting can be reduced by attaching indicators to the tool. However, attaching said indicators is very complicated.
A further configuration for the coupling between cutting head and shank is known from U.S. Pat. No. 6,905,278. The coupling in this case is configured as a screwing insert having a differential thread. For this purpose, the screwing insert has two threads with different pitches. One of the threads is configured as a left-hand thread and the other as a right-hand thread. First of all, the fine thread is screwed into the respective threaded part. In a further operation, the standard or coarse thread is screwed into the other threaded part, as a result of which both coupling members, that is to say cutting head and shank, are effectively restrained against one another.